When I was in the army, they had filters. The problem I had wasn't that I wanted to look at porn or anything silly, but that even legit e-mail sites were locked out. Being a programmer, with access to a linux box that was outside of the network, I wrote a perl script that allowed me to type in the URL, and it used the LWP module to retrieve the HTML, added a base tag to the HTML (to expand all relative paths) and modified the links so that it referenced my perl program, so that it could get the HTML for the HREF'd page, and saved the HTML file on to the server (the linux box running perl, which was also a web-server). I suppose the concept is a proxy, but when someone can program, you have just lost over half of your power to lock them out of things.